While greenhouses, cold frames, cloches and horticultural fleece can all be deployed to extend the growing season and protect a wide range of crops, that still means going out into the cold to harvest them. Much as I love the outdoors, when temperatures plummet the prospect of venturing into the garden to pick, with numb fingers, a few leaves for a sandwich or to flavour the evening meal becomes much less tempting!
The solution is to bring the plants indoors. Not all crops are suitable for this treatment, but some salads and herbs will thrive on a sunny windowsill, providing tasty fresh pickings for longer.
Most leafy salads will continue to grow and produce harvestable leaves in winter, albeit at a slower rate than in the brighter days of summer. Cut-and-come-again or baby leaf crops are best – rocket, spinach and non-heading varieties of lettuce are all sound choices. Dig the plants up, making sure to include as much of the rootball as possible. Shake off loose soil and transplant into multipurpose potting compost.
If you don’t currently have salads growing in your garden to transplant, you can buy ‘living salad’ mixes (which are often made up of varieties of loose-leaf lettuce) from supermarkets and other stores. Carefully tease the roots of individual plants apart, pot them up and grow them on. Each plant will grow larger and produce more leaves when given more room than they had in their tray, so you’ll get more for your money this way too.
Sprouts and microgreens are two more hassle-free indoor crops to keep you in fresh salad ingredients throughout winter.
Evergreen perennial herbs such as oregano, thyme and rosemary work well as indoor winter crops. They won’t grow much during the winter, but they will provide harvestable leaves and they will look and smell great! Oregano and rosemary grow too large for most windowsills, so choose young plants from the garden. It can be worth propagating herbs in advance, specifically for this purpose. In particular, it’s worth taking cuttings of rosemary because it has a tendency to die off in cold, damp weather. By having a few propagated ‘spares’ somewhere sheltered you can insure yourself against the potential loss of a prized rosemary bush over winter.
Chives can be persuaded to crop for longer when brought indoors in winter, and growing parsley on a windowsill will help keep its leaves in good condition.
Growing Salads and Herbs on Your Windowsill
If your plants are already growing in containers, it couldn’t be simpler – just bring them straight in and pop them onto the windowsill.
Dig up plants growing in the ground and pot them up into multipurpose potting compost. Parsley has a long taproot, so when digging it up make sure to dig deeply to get as much of the root as possible, and plant into a pot tall enough to accommodate the root.
There’s no need to bring plants indoors straight away. In fact, they may even benefit from being left outdoors while they adjust to life in a container, but keep an eye on the weather forecast and bring them in before the first hard freeze. Choose your sunniest windowsill for your indoor winter crops, or supplement the light with grow lights.
Check plants over for pests before bringing them in. Believe me, a household infestation of tiny aphids is an annoyance you can live without! Keep plants separate from any permanent houseplants you already have to avoid the risk of transmitting any pests or diseases. Common pests of indoor crops are aphids, whitefly, mealybugs and spider mites.
Only water your overwintering crops once the soil is dry a couple of centimetres/one inch below the potting soil surface. Poke your finger in to check.
Harvesting Windowsill Salads and Herbs
Pick just a few leaves from each plant at a time and allow them time to regrow. Growth will typically slow right down during the shortest days of winter – and may even stop – but your plants will regain momentum as days lengthen.
Harvest evergreen perennial herbs little and often so as not to exhaust them. Chives can be harvested until all the leaves are gone then the plant returned to the garden. Plant it back in the ground if it isn’t frozen, or else leave the pot somewhere sheltered to wait out the rest of the winter. Sooner or later parsley will start to become tough and prepare to go to seed, so harvest as much as you like while it’s still good.
In spring, harden off plants before moving the pots back outdoors or transplanting your perennial herbs back into garden soil. You may continue to get some more pickings of parsley and salads but lengthening days will trigger them to flower and set seed. At this point you can either chuck them onto the compost heap or leave them to flower to feed early-flying insects.
Allow perennial herbs to rest for several months or even a year to give them a chance to recover from the continuous harvesting. For this reason I like to have some growing outdoors as well as indoors in winter, so I can pick up where I left off with well-rested plants.